<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin:0;
            padding:0;
            list-style:none;
        }
        html,body,#app {
            width: 100vw;
            height:100vh;
        }
    </style>
</head>
<body>
    <div id="app">
        <span id="a"></span>
        <div style="width:100%;height:100px;display:table-cell;vertical-align: bottom;border: 1px black solid;">咕咕咕咕咕咕过</div>
    </div>
    <script>
        var a = +new Date()
        console.log(a);
        console.log(a.toString());
        document.getElementById("a").innerHTML = a.toString()
    </script>
</body>
</html>